Amorphous silicon carbide film and photovoltaic device using the same

Abstract

In the present invention, the optical band gap Eg (eV) of an amorphous silicon carbide film has the following relationship with the content of hydrogen CH (at. %) and the content of carbon CC (at. %) in the film: Eg=a+bCH/100+cCC/100, where a, b, and c are respectively in the ranges of 1.54</=a</=1.60, 0.55</=b</=0.65, and -0.65</=c</=-0.55, whereby the defect density in the amorphous silicon carbide film can be significantly reduced.

What is claimed is: 
     
       1. An amorphous silicon carbide semiconductor, wherein the optical band gap Eg (eV) of the semiconductor has the following relationship with the content of hydrogen C H  (at. %) and the content of carbon C C  (at. %) in the semiconductor:   Eg=a+bC.sub.H /100+cC.sub.C /100,     where a, b, and c are respectively in the ranges of 1.54≦a≦1.60, 0.55≦b≦0.65, and -0.65≦c≦-0.55.     
     
     
       2. The amorphous silicon carbide semiconductor according to claim 1, wherein the content of hydrogen C H  in said semiconductor is in the range of 10 to 30 at. %.   
     
     
       3. A photovoltaic device comprising a power generating portion comprising a p-type amorphous semiconductor layer, an i-type amorphous semiconductor layer, and an n-type amorphous semiconductor layer, wherein said i-type amorphous semiconductor layer comprises an amorphous silicon carbide film whose optical band gap Eg (eV) has the following relationship with the content of hydrogen C H  (at. %) and the content of carbon C C  (at. %) in the film:   Eg=a+bC.sub.H /100+cC.sub.C /100,     where a, b, and c are respectively in the ranges of 1.54≦a≦1.60, 0.55≦b≦0.65, and -0.65≦c≦-0.55.     
     
     
       4. The photovoltaic device according to claim 3, wherein the content of hydrogen C H  in said amorphous silicon carbide film is in the range of 10 to 30 at. %.   
     
     
       5. A photovoltaic device comprising a power generating portion comprising a p-type amorphous semiconductor layer, an i-type amorphous semiconductor layer, and an n-type amorphous semiconductor layer, wherein a buffer layer comprising an intrinsic amorphous semiconductor material is provided between said p-type amorphous semiconductor layer and the i-type layer, and   said buffer layer comprises an amorphous silicon carbide film whose optical band gap Eg (eV) has the following relationship with the content of hydrogen C H  (at. %) and the content of carbon C C  (at. %) in the film:   Eg=a+bC.sub.H /100+cC.sub.C /100,     where a, b, and c are respectively in the ranges of 1,54≦a≦1.60, 0.55≦b≦0.65, and -0.65≦c≦-0.55.     
     
     
       6. The photovoltaic device according to claim 5, wherein the content of hydrogen C H  in said amorphous silicon carbide film is in the range of 10 to 30 at. %.   
     
     
       7. The photovoltaic device according to claim 5, wherein a plurality of power generating portions are laminated.   
     
     
       8. A photovoltaic device comprising a plurality of power generating portions laminated together, each portion comprising a p-type amorphous semiconductor layer, an i-type amorphous semiconductor layer, and an n-type amorphous semiconductor layer, wherein said i-type amorphous semiconductor layer of said power generating portion positioned on the side of light incidence comprises an amorphous silicon carbide film whose optical band gap Eg (eV) has the following relationship with the content of hydrogen C H  (at. %) and the content of carbon C C  (at. %) in the film:   Eg=a+bC.sub.H /100+cC.sub.C /100,     wherein a, b, and c are respectively in the ranges of 1.54≦a≦1.60, 0.55≦b≦0.65, and -0.65≦c≦-0.55.     
     
     
       9. The photovoltaic device according to claim 8, wherein the content of hydrogen C H  in said amorphous silicon carbide film is in the range of 10 to 30 at. %.